The news that Bruno Guillon has stepped down from Mulberry won't have come as a great surprise to the British fashion industry. Once a shining example of Brit accessory design, it has floundered under Guillon, with the share price falling 67% in the two years he has been in charge.

His mistake was attempting to fix something that wasn't broken. Throughout the noughties, Mulberry had built its reputation on comparatively affordable luxury accessories – and at one point had seen sales rise 207% in a year. A Mulberry bag was, on average, about £600. Expensive, yes, but a snip when compared with the four-figure prices that came as standard for other luxury accessories – notably, Hermès, Guillon's previous employer. The French house's most famous bag, the Birkin, is about £5,000.

Enter Guillon in 2012. His strategy was to beat the more established luxury brands at their own game, by making the 40-year Somerset brand more exclusive and international. He increased the quality of the leather, and the prices – effectively pricing out a large swath of women who had flocked to Mulberry to buy their first designer handbag. Sales dipped almost immediately. A profit warning came in September 2012 and, instead of increasing international sales, orders from South Korea were cancelled earlier this year.

Guillon's strategy was in direct contrast to that of Emma Hill, the brand's creative director since 2007. Hill resigned last summer amid rumours of disagreements with Guillon. Under her direction, Mulberry made a success out of peddling a firmly British brand. Shows at London fashion week were starry affairs, with dogs on the catwalk and Kate Moss and Alexa Chung in the front row. Designs like the Alexa – based on a vintage men's satchel that the TV presenter was snapped carrying – became hits, and Hill revived the brand's Bayswater design. Losing her was a big warning sign.

Nearly a year on, a new designer has still not been found – although London talent from Sophie Hulme to Erdem Moralioğlu have been mooted for the role. Instead, the brand has gone from having a hard-won image to feeling a little directionless.

It was announced only two weeks before London fashion week that Mulberry would not be showing. Instead, a collaboration with the model Cara Delevingne was revealed to journalists in a back room of the Claridge's hotel.

While Delevingne's collection will no doubt appeal to the Instagramming generation, it felt like too little too late. Guillon's departure is the ending of a chapter of Mulberry's history – one that it will be glad to close.